Veterinary Article

Carbon foot printsfrom dairy cattle
T. K. S. Rao ( 1 ), A. Singh ( 2 ), K. R. Sriranga ( 3 ), S. Chaurasia ( 4 )
Vanbandhu College of Veterinary Science & Animal Husbandry
Navsari Agricultural University, Navsari
396 450 Gujarat India
( 1, 4 )Assistant Professor, e-mail: [email protected]; ( 2,3) M. V. Sc.Scholar at Bikaner & Navsari;
“Opportunities to reduce methane emission by increasing productivity of animalsare larger in extensive rather intensive system in other words, more milk per cow releases less methane per liter of milk at farm”

Carbon foot print is defined as total greenhouse gas (GHG) emission caused directly or indirectly by an animal/ farm in a given time. It is measured in terms of CO2 equivalent (CO2-e) i.e., in terms of environmental heat capturing ability. CO2 equivalent for CH4 is 23 and N2O is 298.In other words N2O is about 300 times more powerful than CO2 in trapping heat in the atmosphere. Agriculture sector alone contributes 15% of total GHG emission of which livestock contributes half of it. Atmosphere contains greenhouse gas naturally that captures heat and keep the surface of earth warm. Greenhouse gases build up due to industrial revolution creating global warming of atmosphere.CH4 in atmosphere has increased by 143% during past two centuries.Ruminants are main contributor to CH4 production.Two main factors which influence global warming is depletion of ozone layer and increase GHG emissions.
With the growing population our focus is shifting towards reducing Greenhouse gas emission per unit of agricultural product i.e., carbon foot print of agricultural product. How we will be able to feed billions without harming our environment? Feed conversion efficiency is one of the most important points for lowering carbon foot print from the dairy animals.

GHG present in environment: GHG includewater vapor, O3, CO2, CH4 and N2O.  Carbon dioxide, methane and Nitrous oxide have direct global warming effect and there concentration depends mainly on human activities.

Emission of GHG from cattle:

  • N2O per cow per day 2-9.9 mg
  • CO2 per cow per day 5309 liters, [Cow producing 5-55 liter milk per day] or 0.14 g per kg of milk (Casper and Mertens, 2010). It is also reported that CO2 production is less in high producing cow. However CO2 emission increases with high dry matter intake and high milk production.
  • Main source of CH4is from enteric (75%) and manure emission.

Greenhouse gas emission at dairy farm:


Carbon dioxide

Nitrous oxide

  • Enteric
  • From manure
  • Machinery at farm
  • Dairy equipment
  • Feed used
  • Slurry storage
  • Inorganic fertilizer
  • Ploughed soil

Mitigation of methane:
Improving health and welfare by proper heat detection, reducing calving problems & milk fever, transition stage feeding brewers grain, bread waste, supplementation with whole cottonseed (Grainger et al., 2008b), reducing lameness, mastitis. Milk production optimized. Lowering pH of slurry, storing manure outdoor to expose high temperature, using anaerobic digester, deep cooling of manures, reducing age at first calving etc.

Mitigation of CO2:
Dairy farm equipment running cautiously saving fuel and energy by putting on/off. Regular servicing of machines engine, Using alternative energy source such as sun light, biogas etc.

Mitigation of N2O:
Careful use of nitrogen and better use of slurry & manure, Using leguminous fodder cut short nitrogen use, Dietary protein modulation

Methane production per cow:

A cow produces 100 kg methane per year and it hardly affected by production, therefore more milk per cow releases less methane per liter of milk

Enteric methane loss in cow:

Rumen is large hollow muscular organ where microbial fermentation takes place. It holds 150-250 liters of material along with 150 billion microorganismsper tea spoon are present in its content. Presence of bacteria in rumen favors production of gases in vat.  CO2 and CH4 are the largest constituents. Generally CO2 is two to three times higher than CH4, although a large quantity of CO2 is reduced to CH4.   Approximately 5500-11000 liters of ruminal gas released by fermentation are eructed/ belched per day is main source of GHG emission.

            About 90% of methane emitted by ruminants released from fermentation in rumen and rest 10% from hindgut (Joblin, 1998). Methanogens microbes convert CO2 and H2 to methane. Out of total methane produced 90% released through mouth and nostril by eructation and rest 10% is emitted from anus. 
            The enteric methane loss in cow is reduced by feeding highly digestible feeds, less forage feeding, more concentrate feeding, ionophores supplementation and adding fats and oils in ration will ultimately improve rumen fermentation, productivity and efficiency.The feed conversion efficiency was most important driver for reducing enteric methane emissions (Gollnow et al., 2014).

Carbon foot prints (Greenhouse gas/Kg of product) from dairy product:Survey and analysis at Canada, 2006 reported highest carbon foot print for milk powder among dairy products.

Milk and milk product:

S. No.


Kg CO2 e/Kg of food product











Sour cream






Fluid milk



Butter milk



Frozen dairy product



Milk powder



Concentrated milk





Different types of Meats, milk and egg: 

S. No.

1 Kg of meat

Produces CO2 e Kg

Produces CO2 e per Kg of protein



















1.11 (Fat and protein corrected milk)







Carbon foot printper unit of proteins several time higher for beef as compared to other animal product because of relatively low fecundity of cattle and produce large amount of methane during feed digestion and they are far less efficient user of their feeds.

  • Recent finding suggest that beef requires 28 times more land to produce meat as compared to pork and chicken,they also require 11 times more water and emits 5 times more GHG. When compared with potato, wheat and rice the impact of beef per calories the requirement is 160 times more for land and emission is 11 times higher.


“Avoiding excessive meat consumption, especially beef is very good for environment”.

Diets of meat lover cause double GHG warming emission as compared to vegetarian diets.Nobel Prize winner of 1921, Albert Einstein once said “Human health and longevity will improve only by shifting towards vegetarian diets”.

Estimation of carbon foot print:

Carbon foot print estimates always expressed in terms of a mass of ‘carbon dioxide equivalent’ or Kg CO2e per unit of product.  Carbon dioxide equivalent used to compare different green-house gas using their global warming potential (GWP), which account for their capacity to absorb radiation and residence time in environment. Formula for calculation of CO2 equivalent is as follow:

CO2 e = CO2 x 1 + CH4x 25 + N2O x 298

  • Carbon foot print of cattle feed calculated by life cycle assessment i.e., LCA (Mogensen et al., 2014).


  • Carbon credit is trade certificate, permit representing the right to emit one ton of carbon dioxide or the mass of another greenhouse gases with a carbon dioxide equivalent (tCO2e) equivalent to one ton of carbon dioxide.

1 carbon credit = 1 ton of CO2 or its equivalent greenhouse gas (GHG)

  • Carbon credits form a marketfor reducing greenhouse emissions by giving a monetaryvalue to the cost of polluting the air (Amit et al., 2014).


Feeds and fodders:

Fodder and crops that are heavily fertilized tend to produce high carbon foot print as compared to crop and fodder that can fix nitrogen and are not fertilized i.e., soybean & alfalfa, however on dry matter production basis heavily fertilized crop showed low carbon foot print due to their high production rate.

  • Pasture species likePhalaris and Fescue are deeper rooted which places organic carbon deeper in the soil. However, animal owners are not using these species due to its low milk production ability.


  • Increasing use of Phosphorus and lower nitrogen fertilizer may supposed to sequester additional carbon/hectare on farm, as we are utilizing low to medium rate of phosphorus. 


Strategies to mitigate enteric methane emission

Expected % reduction in emission

Tannin containing forage
(Graingeret al., 2009)


Replacing barley with corn


Fat and oil seed






Corn and Grain silage


High grain diet



Management options:

Unproductive cow may be culled from herd to reduce emissions.

Rumen manipulation and supplementation:

Removal of protozoa from rumen i.e., specific de-faunationreduces carbon foot print in herd. Yeast and DFM (Direct fed microbial) improve rumen ecosystem with respect to carbon foot print. Monensin reduces CO2 emission by suppressing feed intake and acetate production thereby reducing total hydrogen released(Grainger et al., 2008a). Bovine-somato-tropic (BST) hormones supposed to decrease methane emission by 7-9%. Curry spices like oregano(ajwine in hindi) and garlic also reported to decrease methane release by 40%. However result of long term use may not be effective.
Brewers’ grain and distillery products with available fiber results in methane production half to a third as compared to common food stuffs of similar digestibility.
Forage processing like grinding and pelleting of forage markedly reduces methane production (Blaxter, 1989) reduction is up to 40%. Increased rate of passage of processed forage is likely cause of reduction in GHG emission.
Higher acetogens in rumen may result in lower methane production.
            Fat addition to the diet of cattle reduces methane emission by 37%. Probable mechanism is bio-dehydrogenation of unsaturated fatty acid which enhances propionic acid production and protozoal inhibition.
Vaccination against methanogens in rumen was tried to reduce methane emission with significant result in advanced country.


            Handling manure in form of solid material reduces GHG emission; manure can be stored solid and liquid separately.Anaerobic digestion reduces N2O emissions when slurry is applied to land by decreasing the available N.

Manure storage and treatment system:

            Cover can be used to collect the gases generated during storage.Methane from manure management represents 7% of total methane emission of dairy cows.Reduction potentials were identified for efficient manure management practices (Gollnow et al., 2014). Increasing manure storage time and covering manure with storage structures will supposedto reduce emission.

Management of grazing area:

            Strip,Rotational and intensive grazing system will help in reducing emissions.Reduced stocking rate and minimized grazing period increases soil aeration and reduction in emission.

Reduction of emission per animal:

            Increasing livestock production reduces emission per unit of product. Feeding animals with high grade pasture is best option for dairy farmers. Offering high grade diet favors higher intake and accordingly improve production.  With the increase of daily feed intake methane emission as a percentage of dietary gross energy will decline.

More food less carbon foot prints (GHG):

            Developed countries claim thatthey decreased emission through the breeding higher yielding and more productive animalsby improving crop and fodder production, feeding leguminous crop and adoption of improved land management practices.

Herd management:

            Scientific herd management including selection of breed, and animals with, less age at first breeding, lower calving interval, ration balancing, increased feed efficiency and preparation of TMR (Total Mixed Ration) block will shift GHG emission to lower side.

Nitrous oxide reduction from livestock:

            Animal waste is sole source of nitrous oxide released during both storage and treatment by process of nitrification and de-nitrification. Increase demand of meat and dairy product led to increase in animal wastes. Intensive production system and feed cultivation further increase Nitrogen fertilizer use and emission of nitrous oxide.

Strategies to mitigate:

  • Better targeted fertilizer application
  • Properly well-versed land use practice
  • Livestock waste management like subsurface injection of liquid waste reduces nitrous oxide emission as compared to surface application to open pasture.
  • Rapid incorporation; use of injection methods; use ofchemical nitrification inhibitors help to reduce N2O emission.


Effect of grazing reduces warming in temperate area (New finding):

            On arrival of winter, tall un-grazed grasses trap the snow, forming an insulating blanket that keeps the soil below at relatively warm 16oF or so.Grazing is like trimming, which keeps grasses short. On grazed land, by contrast the snow wash away exposing ground directly to chilly air and driving surface temperature down to a few degrees below zero.
            Grazing reduces N2O emission is proved especially in temperate climate however livestock generate heat trapping methane when they take this.

Green-house gas sequestration:

            Vegetation sinkis supposed to be a major point for sequestering CO2. Carbon sequestration refers to combination of activity which removes CO2 from atmosphere by “locking up” carbon in solid state through process of photosynthesis to produce complex carbon molecules used for plant growth releasing O2 and water in process. Water bodies along with soil are also able to sequester carbon.
            Potential additional profit of plantation include salinity reduction, nutrient buffer strips, shade and shelter with clean and green agricultural system. Thus carbon sequestration is possible by both increasing carbon input and decreasing carbon outputto the system.

Conclusion: Meat and dairy product should be restricted in diet to reduce our carbon foot print and to reduce negative impact on the environment. Metabolic andfeed efficiency required to be improved along with ration balancing nutrition and feeding management in cattle. Cropping process and technologies required to be strengthen. Management is also a very crucial step i.e., storage, processing and application of feed is required to be revisited at farm for reducing carbon foot print. Greenhouse gas emissions at farm include mainly CO2, CH4 and N2O. Mitigation GHG include combination of management practices like Improving health and welfare of animals, maintenance of engines, using alternative energy source and manure management. 


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